Electric watch having transistor controlled contact



July 16, 1963 R. M. JACKSON 3,098,135

ELECTRIC WATCH HAVING TRANSISTOR CONTROLLED CONTACT Filed Aug. 20, 1957 INYENTOR 98 RODERICK M. JACKSON FIG 5 WIDE L i ll was 1111/ BY W ATTORNEY United States Patent Pennsylvania Filed Aug. 20, 1957, Ser. No. 679,208 6 Claims. (Cl. 318-128) This invention relates to i'sochronal devices and electric watches and more particularly relates to a moving coil electric watch having novel means for energizing the moving coil.

in assignees copendin-g applications Serial Nos. 578,843 and 578,844, filed April 17, 1956, now respectively, Patent Nos. 2,972,745 and 2,954,664, there is disclosed an electric watch which has been manufactured in quantity and which has achieved commercial success. This watch utilizes a balance wheel which serves as the frequency controlling element while at the same time supplying mechanical energy to the gear train. In order to accomplish this, the balance wheel carries a coil which passes through a magnetic field as the balance wheel oscillates and which is energized at the moment that it passes through this field to provide the necessary mechanical power pulse. This energization is brought about by connecting the moving coil periodically to a small battery through a novel contact arrangement. This contact arrangement is described in detail in assignees copending application Serial No. 551,791 filed December 8, 1956, now Patent No. 2,954,663.

When it is considered that the contact wire or springs utilized in this contact system have a diameter no larger than the diameter of a human hair, it can be appreciated that the assembly of such a contact system requires a certain amount of manual labor which adds to the cost of the finished watch. Additionally, while the contact system has proven completely satisfactory in service, it does comprise the most fragile portion of the watch and is more susceptible to damage during servicing than any other element of the new electric watch.

I am aware that it has been proposed to utilize transistors in electric watch'construction in order to perform the necessary switching function. To my knowledge, however, such arrangements have thus far been utilized or proposed only in connection with stationary coil watches having movable armatures, so that it is unnecessary to make continuous connection with any electrical component carried by the oscillating balance wheel. All of the prior proposals of which I am aware suggest the addition of a small permanent magnet to the balance wheel, which passes by a pick-up coil in order to control a transistor which in turn controls the switching function for energizing the stationary coil. The magnet is thus carried in a circular path through a good portion of the watch. This creates a moving magnetic field which is detrimental in that it affects the steel par-ts within the watch and makes it necessary to provide non-magnetic balance staffs to prevent a magnetic influence which alters the isochronal behavior of the frequency controlling ele-. ment. Such a moving magnetic field also afiects the spring, since the temperature compensating characteristic essential to quality time pieces is presently achieved by resort to magnetic materials in the hair spring.

According to the present invention I am able to eliminate the contact system utilized in the electric watch shown in the aforementioned copending applications through the use of a transistor switching arrangement which does not necessitate a magnet which moves through a considerable portion of the space within the watch casing. The watch of the invention retains the moving coil carried by the balance wheel, as disclosed in the afore- 3,098,185 Patented July 16, 1963 mentioned applications but, instead of carrying a magnet on the balance wheel, a pallet is utilized to move a small magnet a very small distance to effect the switching function. A transistor is controlled by the switching signal thus produced and provides for energization of the moving coil through suitable connections.

It is accordingly a primary object of the present invention to provide a miniature isochronal device which is both regulated and driven by a periodically energized oscillating coil which does not require commutation for energization.

It is another object of the invention to provide an electric wrist watch which is both regulated and driven by a periodically energized oscillating coil which is supplied with power from a miniature battery without commutation .and without the generation of magnetic fields moving through any substantial portion of the watch casing.

It is a still further object of the invention to provide an electric wrist watch of the foregoing type wherein the periodically energized oscillating coil is carried by the balance wheel which also drives a pallet to control a switching circuit.

These and further objects and advantages of the invention will become more apparent upon reference to the following specification and claims and appended drawings wherein:

FIGURE 1 is a plan view of the train side of an electric watch constructed according to the invention with the balance co ck removed;

FIGURE 2 is a vertical elevation of the watch of FIG- URE 1 with the battery removed;

FIGURE 3 is a partial cross section showing the double hair spring arrangement utilized to provide connections to the moving coil;

FIGURE 4 is a partial plan view of a pallet constructed according to another embodiment of the invention; and

FIGURE 5 is a partial vertical elevation of the pallet of FIGURE 4 showing its relationship to the permanent magnet with which it is associated.

Referring to FIGURES l-3, there is seen an electric watch 10 constructed according to our invention. The watch 10, as seen from the train side in FIGURE 1, comprises a pillar plate 12 which supports a battery 14 held in place by means of a clip 16 and spring 18. Further details of the battery mounting may be found in assignees copending application Serial No. 563,927 filed February 7, 1956, now Patent No. 2,907,810.

A balance staff 20 carries a balance wheel 22 having a sector-shaped coil 24 secured to the rim of the wheel by means of clamps 26 and 28. A roller table 30 is carried on the balance staff 20 above the balance wheel 22 and carries a pin 32 which cooperates with the tork 34 of a pallet 36. The pallet 36 is journaled on a staff 38 and has an outwardly extending end 40. The sector-shaped coil 24 has one end thereof connected to a contact 42 which terminates on the roller table 30 at 44. The other terminal of the coil is grounded to the frame of the balance wheel and thus is connected to the balance staff 20. Further details of the construction of the balance wheel and coil and the clamping and contact arrangement may be had upon reference to assignees copending application Serial No. 578,843 filed April 17, 1956.

The pillar plate 12 is provided with a sector-shaped slot 46 under the balance Wheel 22 and adjacent to the inner portion of this slot the pillar plate is apertured to receive- 'a pair of cylindrical magnets 48 and 50' which are press-.

. being placed sothat opposite poles are uppermost.

An upper shunt 52 is supported by a pair of sleeves 54 and 56 of soft magnetic material which extend through the pillar plate 12. Screws 58 and 60 pass through the upper shunt and sleeves 54 and 56. Both screws and sleeves engage a lower shunt, not shown, which is held against the bottom of the pillar plate, as shown in further detail in assignees aforementioned copending applications, Serial Nos. 578,843 and 478,844. The pillar plate 12 is formed of a suitable non-magnetic material such as brass, nickel or silver, while the shunt and sleeves are formed of a magnetic material such as low-carbon steel. The screws 58 and 60 may be either a magnetic or a nonmagnetic mater-ial, the sleeves 54 and 56 serving to connect the upper and lower shunts magnetically.

The upper end of the balance staff 20 is received in a balance cock 62. The balance staff carries a lower hair spring 64 which is connected direct to the balance staff so as to make electrical contact therewith. The outer end of this hair spring is carried by a metal stud 66 mounted in the balance cock 62 in electric contact therewith. An upper hair spring 68 is also carried by the balance staff 20 above the lower hair spring 64, but the upper hair spring is mounted on an insulating collar 70 which pre vents the hair spring from making electrical contact with the balance staff. The outer end of this hair spring is received in :a metal stud '72 mounted in the balance cock 62 in an insulating bushing 74, so that the stud does not make electric contact therewith.

It will be seen that the lower hair spring 64 is connected to the grounded end of sector-shaped coil 24 by reason of the fact that it makes electric contact with the balance staff 20. The outer end of this hair spring thus connects the grounded end of the coil to the frame of the watch through the balance cock 62 and this is indicated as a ground connection. The other terminal of the sector-shaped coil, which is electrically connected to the contact end 44 on roller plate 30, is connected to the inner end of the upper balance spring as shown at 76. This connection is carried through the hair spring and stud 72. Referring to FIGURE 3, it is seen that the insulated stud 72 is connected to one terminal of the battery 14 while the other terminal of the battery is connected to the collector 78 of a transistor 88.

Referring again to FIGURE 1, it is seen that the outer end 40 of the pallet 36 carries a U-shaped arm 82 which carries a tiny permanent magnet on its outer end. In the mid-position of the pallet, as shown in FIGURE 1, the magnet is received within a small helical coil 84 which is secured to the watch frame by means of a small bracket 86 and screw 88. It will be apparent that as the balance wheel 22 oscillates, the pallet 36 causes the small magnet at the end thereof to move into and out of the coil 84, the magnet moving in and out once for each oscillation of the balance wheel.

A pair of banking pins 83 and 85 are positioned at either side of the pallet end 40 and are made of small permanent magnets. The banking pins serve the dual function of limiting the extent of movement of the pallet, which is preferably formed of a magnetic material, and also of holding the pallet in position between mechanical impulses from the pin 32 on the roller table 30.

Referring to FIGURE 3, the coil 84 has its terminals respectively connected to the emitter 90 and the base 92 of transistor 80. The emitter 90 is grounded as shown at 94. It will be seen that when the transistor 80 conducts, the battery 14 is connected to supply power to the sector-shaped coil 24, carried by the balance wheel 22. This circuit extends from one terminal of the battery 14 through stud 72, hair spring 68 and connection 76 to the coil. The other terminal of the coil is connected to the balance staff 20 and thence through lower hair spring 64, stud 66, the watch frame, emitter 90 and collector 78 back to the battery to supply power to the coil. The emitter is caused to conduct during that period of time that the coil 84 generates a voltage sufficient to bias the transistor to conduction. While the coil 84 generates a voltage once as the magnet moves in and once again as the magnet moves out during each oscillation, only one of these voltages has a polarity which causes the transistor to conduct so that the moving coil is connected to the battery only once per oscillation to always impulse the balance wheel in the same direction.

it will be apparent that the foregoing arrangement eliminates the contacts previously utilized in this type of watch without creating stray magnetic fields moving through a large area of the watch casing. Not only is the small magnet at the end of the pallet constrained to move only through a small distance, but it is also possible to magnetically shield this coil if an even further reduction of stray fields is desired. The arrangement is simple in nature and considerably reduces the labor necessary in assembling electric watches.

While the foregoing embodiment of the invention shows the use of a movable magnet, it is also possible to utilize a moving coil on the pallet end. Thus referring to FIG- URES 4 and 5, there is shown a pallet 96 carried by a staff 98 and having a tiny coil 100 mounted on the end thereof. One terminal of the coil 100 is grounded to the metal pallet 96 while the other terminal is coiled pig-tail fashion about the staff 98, as shown at 102. A small cylindrical magnet 104 is mounted on the Watch frame immediately adjacent the coil 100 so that each time the pallet causes the coil 100 to pass over the magnet 104 a voltage is generated in the coil 100. The coil 100 may be connected in the same manner as the coil 84 in the preceding embodiment of the invention to provide a voltage impulse to bias the transistor to conduction periodically as the pallet is caused to move. As with the preceding embodiment of the invention, movement of the coil in one direction is effective to bias the transistor to conduction, whereas movement of the coil in the other direction presents a voltage of the wrong polarity to cause conduction, so that no conduction occurs.

The invention maybe embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. An electric timepiece comprising a coil mounted for oscillation on a balance staff, means in said timepiece for creating a relatively concentrated magnetic field through which said mounted coil moves, a battery for energizing said coil periodically, a semi-conductor switching device for connecting said battery to said mounted coil, a control means actuated by oscillation of said balance staff but separate therefrom, said control means being so constructed that its circular movement is less than the circular movement of the balance staff, and means connecting the control means to the switching device so that the operation of the control means will cause periodic energization of said mounted coil in synchronism with the oscillation of said staff.

2. An electric timepiece comprising a coil mounted for oscillation on a balance staff, means in said timepiece for creating a relatively concentrated magnetic field through which said mounted coil moves, a battery for energizing said coil periodically, a semi-conductor device for conmeeting said battery to said mounted coil, a control means actuated by oscillation of said balance staff, said control means comprising a coil and a second magnet movable relative to one another, said movement taking place on each oscillation of said balance staff, the maximum movement of said magnet being substantially less than the movement of said balance staff during the oscillation thereof, and means connecting the control means to the switching device so that the operation of the control means will cause periodic energization of said mounted coil in synchronism with the oscillation of said staif.

3. An electric timepiece as set out in claim 2 including a pair of hairsprings mounted on said staff, and said coil being electrically connected between said pair of hairsprings.

4. An electric timepiece comprising a coil mounted for oscillation on a balance staff, means in said timepiece for creating a relatively concentrated magnetic field through which said mounted coil moves, a battery for energizing said coil periodically, a semiconductor switching device for connecting said battery to said mounted coil, a pin carried by said staff, a pallet mounted for oscillation in synchronism with the oscillation of said staff, the said pallet being provided with a means at one end engageable with said pin, and a control means actuated by the movement of the pallet, said control means consisting of a sec ond coil mounted adjacent a magnetic field producing means so that movement of said pallet causes relative movement between the said second coil and said magnetic field producing means thereby causing periodic energization of said mounted coil in synchronism with the oscillation of said staif.

5. A miniature isochronal device comprising a coil mounted for oscillation on a stalf, means creating :a mag netic field through which said coil moves, a battery for energizing said coil periodically, semi-conductor switching means for connecting said battery to said mounted coil, a pin carried by said staff, :a pallet mounted for oscillation in synchronism with the oscillations of said staff, the said pallet being provided with -a means at one end engageable with said pin and a magnet on the other end,

a stationary coil mounted adjacent the other end of said pallet, and means connecting the stationary coil to the switching means, whereby movement of said pallet causes relative movement between said coil and said magnet to produce a control signal for said switching device.

6. A miniature isoohronal device comprising a coil mounted for oscillation on a staff, means creating a magnetic field through which said coil moves, a battery for energizing said coil periodically, semi-conductor switching means fior connecting said battery to said mounted coil, a pin carried by said staff, a pallet mounted for oscillation in synchronism with the oscillation of said stafi, the said pallet being provided with a means at one end engageable with said pin and a coil on the other end, means creating a magnetic field mounted adjacent the other end of said pallet, and means connecting the coil mounted on the pallet to the switching means, whereby' movement of said pallet causes relative movement between said coil and said magnetic field producing means to produce a control signal for said switching device.

References Cited in the file of this patent UNITED STATES PATENTS 2,598,912 Held June 3, 1952 2,769,946 Brai-lsfiord Nov. 6, 1956 2,835,105 Favey May 20, 1958 FOREIGN PATENTS 410,554 Great Britain May 24, 1934 764,450 Great Britain Dec. 28, 1956 1,092,411 France Nov. 10, 1954 1,117,873 France Mar. 5, 1956 

1. AN ELECTRIC TIMEPIECE COMPRISING A COIL MOUNTED FOR OSCILLATION ON A BALANCE STAFF, MEANS IN SAID TIMEPIECE FOR CREATING A RELATIVELY CONCENTRATED MAGNETIC FIELD THROUGH WHICH SAID MOUNTED COIL MOVES, A BATTERY FOR ENERGIZING SAID COIL PERIODICALLY, SEMI-CONDUCTOR SWITCHING DEVICE FOR CONNECTING SAID BATTERY TO SAID MOUNTED COIL, A CONTROL MEANS ACTUATED BY OSCILLATION OF SAID BALANCE STAFF BUT SEPARATE THEREFROM, SAID CONTROL MEANS BEING SO CONSTRUCTED THAT ITS CIRCULAR MOVEMENT IS LESS THAN THE CIRCULAR MOVEMENT OF THE BALANCE STAFF, AND MEANS CONECTING THE CONTROL MEANS TO THE SWITCHING DEVICE SO THAT THE OPERATION OF THE CONTROL MEANS WILL CAUSE PERIODIC ENERGIZATION OF SAID MOUNTED COIL IN SYNCHRONISM WITH THE OSCILLATION OF SAID STAFF. 